1. Field of the Invention
The present invention relates to an elongated member made entirely or partially of extruded plastic, and suitable for use as the upper surface of decks, docks, or bench type seating, and for other uses, generally in walking, standing, or sitting areas. One form of the invention is a covering member for wooden, metal, or concrete planks or beams.
2. Prior Art
There have been various prior proposals for using plastic extrusions for decking and like flooring needs, and for seating, especially for outdoor use, and our above-mentioned patent and application provide extrusions for such uses. Examples of such constructions are described in the following patents:
Canadian Patent No. 989,134, issued May 18, 1976 to Hassman;
Canadian Patent No. 1,190,717, issued Jul. 23, 1985, to Stanley et al.;
Canadian Patent Application No. 2,100,986, published Jan. 22, 1995, of Steadman; and
Canadian Patent Application No. 2,108,425, published Apr. 15, 1995, of Bayly.
The Canadian patents of Hassman and Stanley et al., and the Steadman application, describe structures formed of polyester resin or like material with glass fiber reinforcement, these structures being formed by pultrusion. The Bayly application describes a plastic channel type member, which seemingly might be extruded, although this does not appear to be mentioned.
It has also been proposed to provide existing wooden, metal, or concrete planks or beams with a cover formed from a plastic extrusion. Covering such a plank with plastic may be desirable, for example, to protect existing wood or to cover wood which has become deteriorated or likely to produce splinters, or for improving the comfort or appearance of a concrete or metal beam. Examples of such plastic extrusions are described in the following patents:
U.S. Pat. No. 5,070,664, which issued Dec. 10, 1991 to Groh. et al., and which describes an extruded plastic structure for fitting onto wooden or steel benches to improve comfort and weather resistance; and
U.S. Pat. No. 5,904,011, which issued May 18, 1999 to Biro, and which describes an extrusion suitable for boat docks and residential decks.
In addition, U.S. Pat. No. 4,840,824 to Davis, and U.S. Pat. No. 4,998,391 to Connew, describe plastic extrusions which may be used as stairtreads.
A common drawback of plastic surfaces for decks and other walking areas is that these tend to be slippery, especially when wet. Some of the prior patents show ribs or other formations intended to provide a non-slip surface. Others have a grit surface or a textured surface.
The Groh et al. patent shows a structure with an overlying cap or xe2x80x9ccapstockxe2x80x9d of between 15 and 25 mils in thickness, formed of a rigid vinyl resin, intended to improve weatherability, and which also has spaced apart, integrally formed, parallel ridges which provide a gripping surface. The Biro patent shows longitudinal upstanding ribs which are extruded, and which are subsequently embossed to form the ribs into pyramid-shaped tread members.
These prior art non-skid features are believed to have some drawbacks. Thus, ribs of the type shown in the Hassman or Groh et al. patents provide little gripping effect in directions parallel to the ribs. In each case, the ribs are formed integrally with the surrounding material and thus have the same hardness or firmness. The actual decking made in accordance with the Groh et al. patent, including the ribs, has a hard surface and lacks friction in the direction of the ribs; tests discussed below give a comparison of the friction achieved with Groh et al. compared to material made in accordance with this invention. Surfaces of the kind described in the Stanley et al patent, or in the Bayly application, are likely to be difficult to produce as part of an extrusion process.
The non-slip features shown by Biro and Connew require additional manufacturing steps beyond a simple extrusion process.
The stairtread products of Davis and Connew use, as anti-slip elements, upwardly projecting rib members which are of softer material than the main body of the stairtread. Where these are recessed into the main body of the stairtread these would weaken the product; however this is unimportant for a stairtread since the main plate portions of the stairtreads are fully supported by the underlying surface.
In Biro, the extrusion has a top plate which is separated by depending ribs or spacer means from the surface, for example the plank, which it covers. The spacer means include channels which receive fasteners and which accommodate covers over the fasteners. The top plate therefore requires some bending strength where it bridges gaps between these spacer means. Accordingly, unlike with the stairtread patents, the top plate does require some strength.
There exists a need for a cover for flooring or decking member, seating member or the like, which can easily be produced by extrusion, preferably without subsequent steps being performed, and which has a non-skid feature which is effective lengthwise of the member and not only in the cross direction. The non-skid feature should also not unduly weaken the top plate.
The present invention provides an elongated member suitable for flooring, decking, or seating, comprising top plate means overlying spacer means suitable for spacing the top plate means above the top surface of the support, the top plate means bridging gaps between the spacer means, both the top plate means and the support being formed by extrusion of plastic material. To overcome the slippery nature of the basic structure, the top plate means has a non-slip surface provided by ribs constituted by portions of parallel, spaced apart, elongated friction elements co-extruded with a main component of the top plate, these elements being formed from plastic material having distinctly greater softness or flexibility than that of the main component which lies between and underneath the friction elements. These elements have their lower portions embedded in the top plate means. However since the top plate means must resist bending, the elements are made so as not to penetrate more than one half the top plate depth, and in some embodiments penetrate only 35% or 25% of the top plate depth.
The ribs in accordance with this invention have a hardness between 50 and 92 Durometer in the Shore A scale, and preferably less than 90 Durometer, and in some cases less than 80 Durometer on the Shore A scale. The softness of the ribs in accordance with this invention is comparable to that of treads on shoes, and gives the ribs enhanced friction in the longitudinal direction, as well as in the transverse direction.
In the preferred embodiments, the friction elements have a hardness of between 75 and 85 Durometer on the Shore A scale, while the main component of the top plate means has a hardness of at least 70 Durometer on the Shore A scale.
Preferably, the ribs protrude from the top plate between 0.02 and 0.05 inches (0.5 to 0.13 mm). The ribs may be integral with a capstock layer which forms part of the top plate means and totally covers the main component.
One embodiment of the invention, which is the subject of our aforesaid copending application, is an all plastic, all extruded, elongated member, for example a hollow flooring member, comprising a top plate means as described overlying a lower support part also formed as an extrusion of plastic material and having a base plate with upstanding side walls and upstanding, longitudinally extending support webs positioned between the side walls, the top plate means bridging gaps between the side walls and webs.
In another embodiment, which is the subject of the issued U.S. Pat. No. 5,826,382 as aforesaid, the top plate means may be formed separately from the support part, and may have inturned edge elements held by interengaging formations at the top of the side walls of the support part.
The present application however is particularity concerned with a form of the invention which is a cover for a support such as a plank or beam of wood, metal, or concrete, in which the spacer means, which are integrally extruded with the top plate means, include two spaced channels having bottom webs suitable for lying on the support top surface and for receiving fasteners to secure the member to the support.